A comparative study of SPE- and DLLME-based methods for the determination of opioids and benzodiazepines in urine samples using LC–MS/MS

Abstract

The determination of drugs of abuse has been gaining increasing attention among the scientific community as drug consumption is considered a major global public health issue. Opioids and benzodiazepines are among the most widely consumed drugs worldwide. Analytical methods for their determination, particularly in urine matrices, primarily rely on chromatographic techniques. However, due to the complexity of the matrix and the low concentration levels at which these drugs are usually present (in the ng/L or µg/L range), efficient sample pre-treatment strategies are essential. This step is of significant importance in the development of environmentally friendly analytical methods. For this reason, in recent years, pre-treatment techniques have been developed based on green analytical chemical principles to address this need.

In this context, we present a comparative study of solid phase extraction (SPE) and dispersive liquid–liquid microextraction (DLLME) for the determination of a group of benzodiazepines and opioids in urine samples using liquid chromatography coupled with tandem mass spectrometry (LC–MS/MS). The method, based on SPE, was developed using ExtraBond SCX as the sorbent and 7 mL of 5 % of NH₄OH in methanol as the elution solvent, yielding recoveries ranging from 9 to 107 %. The DLLME method used 200 µL of chloroform and 500 µL of ethyl acetate as extractant and dispersant solvents, respectively, achieving recoveries between 14 and 86 %. The DLLME strategy proved to be greener than the SPE method in line with the principles of green analytical chemistry (GAC), as it required lower volumes of solvents, a shorter extraction time, and less energy consumption than the SPE method. Both methods were validated using urine matrices and subsequently applied to 11 urine specimens from women participating in detoxification programmes, confirming the suitability of these methods in toxicological and forensic analyses. The results showed that methadone and diazepam were the most frequently determined compounds, and a trend of polyconsumption was observed in most of the samples.